5.Image_segmentation

# Threshold detection methods are used to determine the

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Unformatted text preview: e used to determine the threshold automatically. If some property of an image after segmentation is known a priori, the task of threshold detection is simplified, since the threshold can be selected to ensure that this property is satisfied. Threshold detection can use p-tile thresholding, histogram shape analysis, optimal thresholding, etc.. In bi-modal histograms, the threshold can be determined as a minimum between the two highest local maxima. Optimal thresholding determines the threshold as the closest gray-level corresponding to the minimum probability between the maxima of two or more normal distributions. Such thresholding results in minimum error segmentation Multi spectral thresholding is appropriate for color or multi band images. Faculty of Engineering Robotics Technology MECH 4041 10 B.Eng (Hons.) Mechatronics S. Venkannah Mechanical and Production Engineering Department Thresholding can be also performed in hierarchical data structures, the aim being to detect the presence of a region in a low-resolution image, and to give the region more precision in images of higher to full resolution. Clustering methods: Clustering in pattern recognition is the process of partitioning a set of pattern vectors into subsets called clusters. It consists of finding subsets of points that are “close” to each other in Euclidean two space. Classical clustering methods: The general problem in clustering is to partition a set of vectors into groups having similar values. In image analysis, the vectors represent pixels or sometimes small neighborhoods around pixels. The components of these vectors can include: Intensity values RGB values and color properties derived from them Calculated properties Texture measurements Any feature that can be associated with a pixel can be used to group pixels. Once pixels have been grouped into clusters based on these measurement-space values, it is easy to find connected regions using connected components labeling. In traditional clustering, ther...
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## This document was uploaded on 03/12/2014 for the course MECHANICAL 214 at University of Manchester.

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